Trim components such as trim panels are typically used for covering and finishing the interior passenger cabins of automobiles, aircraft, rail vehicles, etc., as well as luggage areas and some external areas of such vehicles. For example, in automotive applications such trim components include headliners, door liners, armrest pads, storage bins, consoles, dashboard covers, load floors, package trays, pillar covers, trunk liners, engine hood covers, wheel well liners, etc. Especially in the interior trim applications, such trim components are to provide a surface covering that is visually attractive and comfortable to the touch, as well as providing acoustic insulation and damping. In exterior trim applications, such trim components are to provide weather protection, heat shielding, acoustic damping and insulation, and/or other specialized functions. In some applications such as load floors, the trim components also must provide sufficient structural strength for supporting the intended load. For these reasons, trim components are fabricated from a great variety of different materials providing the required functional properties. Typically, a trim component such as a trim panel includes a cover layer (also known as a “decor” layer) laminated onto a substrate, whereby the cover layer provides an attractive appearance or weather protection or heat shielding, etc., and the substrate provides the structural strength and three-dimensional form of the component. One or more additional layers, such as foam padding and thermal or acoustic insulation layers, may be laminated between the cover layer and the substrate. In some applications, a separate cover layer is not required, and the trim component may consist of a single layer that provides both the required structural strength and the required surface characteristic. The substrate may be made of various materials, for example synthetic plastic such as ABS or propylene, fiber board stock including wood fibers or other natural fibers embedded in plastic resin, fiberglass panels, or a hybrid composite including natural fibers together with synthetic plastic fibers, such as a natural fiber and polypropylene fiber composite. The plastic materials of the substrate may include thermoplastic and/or thermoset materials. The cover layer may be made of decorative woven or non-woven fabric, fleece, natural leather, imitation leather, or vinyl or other plastic sheet materials, preferably bonded to a backing of a foam material, such as polyether or polyethylene foam.
Various methods are known for press-molding such trim components. Typically a sheet of the substrate material, a sheet of the cover layer material, and one or more sheets of any intermediate layers are stacked to form a sandwich structure, which is placed between a lower mold and an upper mold of a molding press. The upper and lower molds are closed relative to one another, and thereby the layered sandwich structure is laminated, compressed and three-dimensionally molded, under the effects of heat and pressure between the upper and lower molds. Generally in this regard, the cover layer and substrate materials are thermoformable, i.e. so that they may be heated to a softening or molding temperature, then molded into a desired three-dimensionally contoured shape, and then cooled to become rigid and maintain the contoured shape. However, due to tolerances and misalignments that arise during the laminating and molding process, and due to the stretching and molding deformation of the cover layer and the substrate during the molding process, the various layers are stretched and/or pulled back by differing extents. Therefore, typically the cover layer must be initially provided with oversized dimensions relative to the desired finished size of the resulting laminated trim component to allow for the variable shrinkage or pull-back of the edges of the cover layer (which is difficult to predict). If the amount of shrinkage or pull-back is not exactly correctly predicted and accommodated, then there will be either an excess or a shortage of the cover layer material along the edges of the trim component after the laminating and molding process. Therefore an extra edge-trimming process is often necessary. Even then, it is difficult to neatly cut the edge of the molded trim component to form a neat and clean edge thereof. Also, even if the edge can be neatly cut, it has a visually unattractive appearance and is subject to delaminating or unraveling if this edge is exposed in the final installed condition of the trim component.
To avoid the above problem of forming a neat and clean cut edge of the trim component, it is known to fold the edge of the cover layer around the substrate edge to form an edge-folded rim rather than a cut edge of the trim component. For example, U.S. Pat. No. 5,718,791 discloses a method and an apparatus of laminating a trim panel, and folding a cover sheet edge around the panel's rim in a one-shot process in a single apparatus that performs the molding and laminating of the component between an upper mold and a lower mold, and includes edge-folding tools laterally movably arranged around the perimeter of the upper mold arrangement. The edge-folding tools are effective to fold an excess flange of cover sheet material around the back side of the edge of the substrate in order to produce a neatly finished trim component with the cover sheet edge wrapped or folded around a rim of the substrate. However, even with such edge-folding, it is difficult to pre-determine the correct size of the cover layer necessary to accommodate the stretching and possible pull-back of the cover layer around the edges during the three-dimensional molding and laminating process. Thus, even after the edge-folding, there might be excessive or insufficient cover layer material around the trim component rim. Such a problem is addressed or avoided in U.S. Pat. No. 6,524,506, which discloses a combination tool for carrying out both edge-folding and cutting of the rim of a trim panel.
In some applications it is not desired or not ideal to use a trim component that has the cover layer folded around the edge thereof as described above. For example, the edge-folding of the cover layer requires additional cover layer material, which adds to the cost of the trim component especially when a high-value cover material such as natural leather is used. Namely, the leather cover material folded around the edge of the trim component requires extra leather even though it will not be visible in the final installed condition. Furthermore, when a trim component is installed with its edge abutting against another component, it is often desirable to form an improved seal and finished appearance of the trim component edge against the adjoining or abutting component. For example, it may be desired to provide a flexible and adaptable rim that can seal against the adjoining component within a certain tolerance range to allow for fabrication and installation tolerances or variations, while still achieving a tight-fitting seal, for example to prevent air, noise or dust infiltration, or to achieve a neat, tight-fitting finished appearance.
For these reasons, it has become known to provide an injection-molded rim such as a molded flange, bead or lip along the edge of a press-molded trim component. Conventionally, the trim component body is first press-molded between upper and lower molds of a first molding apparatus, generally as described above. Further steps of preparing the materials of the layer or layers, by heating, pre-compressing, calibrating, pre-laminating, etc. are also well known in the art, and will not be described in further detail here. It is further known that the substrate and/or the cover layer can each be either a single layer or a pre-laminated sandwich of several layers, or several layers can be introduced individually or as a pre-laminated component into the molding apparatus. As needed, the edge of the trim component body is also cut to the appropriate size and shape. The first press-molding apparatus is then opened, and the press-molded trim component body is removed from it and placed into a second injection-molding apparatus. This apparatus for example includes upper and lower injection-mold tools that form an injection-molding cavity around the perimeter of the trim component body. This injection-molding cavity adjoins and is seated and sealed onto the edge portion of the trim component body, plastic is injected into the mold cavity, and is then cooled or cured and thereby hardened to form a plastic frame or rim along the perimeter of the trim component body. The plastic frame or rim is adhered onto the edge portion of the trim component body by the molding process, because the injected plastic material contacts and adheres onto the edge portion of the trim component body under the injection and molding pressure, and then cures in place. During the injection-molding step, it is additionally possible to mold reinforcement ribs, retainers, domes, or other such plastic structures on the back mounting side of the trim component body, while the injection-molded rim is also being produced. Furthermore, the injection-molded rim or frame may be continuous around the entire perimeter of the trim component body, or it may be formed only in certain limited or bounded areas as needed. After the initial cure, the injection-molding tools are opened and the finished component including a plastic frame or rim along the edge of the trim component body is removed from the injection-molding apparatus.
The above conventional production process suffers the disadvantage that it requires two separate procedures carried out sequentially in two separate molding apparatuses, namely first a press-molding process carried out in a press-molding apparatus to form the trim component body, and then secondly an injection-molding process carried out in an injection-molding apparatus to form the plastic frame or rim along the edge of the trim component body. The extra equipment and extra process steps entail additional capital expenditure and additional labor and process costs. Furthermore, it has been found that the bonding or adhesion of the injection-molded plastic frame or rim onto the edge portion of the trim component body may be insufficient. This last problem has been addressed in German Utility Model DE 20 2013 005 670 U1, by providing an improved mechanical engagement between the injection-molded plastic frame or rim and the edge portion of the trim component body, by forming holes, notches or recesses along the edge of the trim component body. The injection-molded plastic engages and bonds into these holes, notches or recesses to achieve improved multi-dimensional adhesion and engagement of the injection-molded rim onto the trim component body.
To address the above disadvantage of conventionally requiring two separate processes in two separate molding apparatuses, German Patent Laying Open Publication DE 10 2014 217 173 A1 discloses a method and an apparatus for forming a molded trim component including an injection-molded rim on a laminated and molded trim panel body. A single apparatus is used to carry out a single process in which a trim panel body is three-dimensionally press-molded, cut to a perimeter shape, provided with an injection-molded rim, and provided with injection-molded or back-molded functional components such as reinforcement ribs on the back side of the panel body. To achieve this, the apparatus includes an upper mold and a lower mold, between which the trim panel body is press-molded. The upper mold and lower mold further include cooperating cutting edges that cut the perimeter edge of the trim panel body as the upper and lower molds close relative to each other. One cutting edge is fixedly provided on the upper mold tool, and the other counter-cutting edge is provided fixedly on the lower mold tool. After the perimeter edge of the trim panel body is cut, the press-molding further proceeds, whereby the cut edge of the trim panel body is pulled back slightly away from the perimeter of the mold cavity due to the pulling deformation of the trim panel body during the press-molding. The area where the cut edge of the trim panel, body has been pulled back away from the edge of the mold cavity forms an injection-molding cavity space into which an injection-molding material is injected through an injection channel or sprue provided in the lower mold. This forms an injection-molded rim bonded or adhered onto the cut edge of the trim panel body. The injection-molded rim forms a clean finished edge of the completed trim component. A reinforcement rib or the like can be simultaneously injection-molded onto the back side of the trim panel body, and adjoins the molded rim.
A problem or disadvantage of the above known method and apparatus is that the final width and shape of the injection-molded rim depends on the extent to which the cut edge of the trim panel body material retracts or pulls back during the final stage of the press-molding after the panel body edge has been cut by the two cooperating cutting edges as the upper and lower mold tools begin to close upon one another. Because of the variable and somewhat unpredictable and imprecise retraction or pull-back of the cut edge of the trim panel body, it is not possible to form a precisely dimensioned and uniform injection-molded rim. Instead, for example, the width of the finished injection-molded rim will depend on, and vary with, the particular local extent of the retraction or pull-back of the cut edge of the trim panel body at each location around the perimeter of the trim panel body. Because different areas will have different amounts of retraction due to different three-dimensional press-molding contours, the width of the finished injection-molded rim will also vary. Furthermore, by mounting the cutting tools fixedly on the upper and lower mold tools respectively, and by forming the injection-molding cavity with the same upper and lower mold tools used for the press-molding, the known apparatus and method provide only limited adaptability for achieving different configurations of the injection-molded rim and the trim component. It is desired to overcome these disadvantages.